The present invention concerns an injection nozzle for use in the addition of an agent in wire form to such as molten steel.
In the steelmaking process, a ferrous melt produced in a suitable furnace is normally tapped into a ladle where it is treated with one or more agents to refine or alloy the melt. A refining agent commonly used to deoxidize, desulfurize and cause other desired solidification characteristics in the steel is calcium. Since calcium is lighter than the steel and is highly reactive, the calcium is preferably added in the form of an iron-clad wire introduced into the melt well below the melt surface through a refractory injection nozzle. A process highly suitable for such calcium addition is disclosed in U.S. Pat. No. 4,481,032.
An apparatus for introducing the calcium wire into the melt in such a process is disclosed in U.S. Pat. No. 4,512,800. With this apparatus, the wire passes through an injection nozzle having an orifice of novel configuration and circular cross section. An inert gas such as argon also passes through the orifice, in the annular space between the wire and orifice wall, and into the bath, the gas pressure in the nozzle being such as to prevent the melt from entering and plugging the orifice.
While the apparatus of U.S. Pat. No. 4,512,800 effectively injects the calcium wire into the melt, a more efficient means for introducing the protective gas into the melt is highly desirable. It is the primary objective of this invention to provide such a means.